DE102009057955A1 - Synchronization method for automatic transmission for vehicles, involves signaling actual speed by transmission shafts at transmission control unit during shifting up or shifting down of gears - Google Patents

Abstract

The synchronization method involves signaling an actual speed by transmission shafts at a transmission control unit during shifting up or shifting down of gears. The desired speed is determined by the transmission control unit, where one of the transmission shafts is accelerated for a preselected gear on the desired speed.

Description

The invention relates to a synchronization method for an automatic transmission for vehicles. When shifting up or down gears, the actual speed of the transmission shafts is signaled to a transmission control unit. For this purpose, a rotational speed at which the synchronizer clutch rotates on one of the transmission shafts in an idling position or in an engagement position with one of the gears of a gear pair of a gear is first measured as the actual rotational speed. A desired speed to which the transmission shaft is to be accelerated or decelerated for a preselected gear is given by the transmission control unit. Synchronization parameters are controlled so that a rapid axial displacement of the synchronizer clutch on the transmission shaft from an idle position to an engaged position of the synchronous clutch of the preselected gear can take place.

In such a rapid upshift or downshift of gears results in an automatic transmission 1 , like it 4 with a dual-clutch transmission shows the peculiarity that when switching from an odd gear, such as V1, V3 or V5, to a straight gear, such as V2, V4 or V6, switching over a first transmission input shaft 8th which the drive gears 31 to 33 the odd gears V1, V3 and V5, and a second transmission input shaft 9 which the drive gears 34 to 36 for the gears V2, V4 and V6, via synchronizer clutches 11 to 14 on a common transmission output shaft 10 with the output gears 40 to 46 are to be operated.

In this case, in order to enable a smooth switching, to operate at each shift change over automatic transmissions with only one engine clutch and a transmission input shaft two synchronizer clutches. With a gear change by two higher or two lower gears even three shifts on synchronizer clutches are to perform to a smooth switching using a first engine clutch 6 and a second engine clutch 7 the double clutch 4 to carry out. This is the requirement for the switching speed of the synchronous clutches 11 to 14 so high that it even with jerk-free switching operation and the use of the double clutch 4 from two engine clutches 6 and 7 can come to Lastwechselgeräuschen in the transmission. To control the shifts, the speeds of the first transmission input shaft 8th with a tachometer 22 , the second transmission input shaft 9 with a tachometer 23 , the transmission output shaft 10 with a tachometer 24 and the speed of the motor shaft 3 with a tachometer 25 monitored and a transmission control unit 15 fed. The transmission control unit 15 automatically initiates the engagement and disengagement of the synchronizer clutches 11 to 14 ,

To discuss the formation of load noise, shows 5 a synchronous coupling 12 according to the prior art, as it is also used for a dual-clutch transmission. The double-sided synchronous coupling shown here 12 is between a driven gear 42 the third forward gear V3 and a driven gear 43 fifth gear V5, with their hubs 48 rotatable on needle bearings 47 opposite the transmission output shaft 10 are stored, arranged. A non-rotatable synchronizer clutch hub 49 the synchronous clutch 12 is non-rotatable with respect to the output shaft 10 between the two hubs 48 stored.

The synchronous clutch hub 49 carries an axle-shifting shift claw 5 the synchronous clutch 12 into which a shift fork 26 engages and the shift claw 5 in the direction of arrow A or B can move axially, with an outer synchronizer ring 39 with his cone 50 a middle synchronizer ring 37 and an inner synchronizer ring 38 frictionally engaged with the hub 48 one of the output gears 42 or 43 decelerates or accelerates until a synchronous operation between the respective output gear 42 or 43 , the synchronizer ring 39 and the shift claw 5 is achieved, so that the shift claw either in the direction A or in the direction of arrow B on dog teeth 29 the output gear hubs 48 can be pushed. If this shift operation with excessive engagement speed or a correspondingly high thrust force, this causes the above-mentioned load change noises, as it is closer to the 6 is explained.

6 _{FIG. 12} is a graph showing the rotational speed n _{LWG of} a transmission output shaft in downshifting to a lower gear, with a dotted line showing the target rotational speed n _soll to which the transmission output shaft is to be accelerated and showing a dot-dash line, as due to high-speed shifting or high force pushed shifting claw, the actual speed _is n α with great steepness' of the target rotational speed n _set approaches and there is an overshoot. A dotted line shows a speed curve n ' _LWG which leads to a lift of intermeshing teeth of a gear, with a slip between the two meshing gears occurs. The slip is completed when both sprockets back with their teeth at time t ₁ and t ₂ comb each other.

Such a re-engagement of the teeth causes load noise, because the sprockets of intermeshing gears of the transmission output shaft or the Gear drive shafts are not engaged for fractions of seconds. Thus, there is a noise, the sprockets or the teeth in the output gear and drive gear at time t ₁ or in the subsequent undershoot at time t ₂ meet again and thus cause the load change noise. These load change noises can also occur with automatic transmissions with only one engine clutch. However, in such transmissions when downshifting and upshifting around a gear only to operate only a double-acting synchronizer clutch, so that here the demand on switching speed and switching forces acting on the shift claw 5 are to act against double-clutch transmissions are reduced.

The object of the invention is to provide a synchronous clutch method for an automatic transmission for vehicles, which overcomes the disadvantages of the prior art and reduces load change noises in synchronization transmissions, especially in dual-clutch transmissions.

This object is achieved with the independent claim 1. Advantageous developments of the invention will become apparent from the dependent claims.

According to the invention, a synchronization method for an automatic transmission for vehicles is provided. When shifting up or down gears, the actual speed of the transmission shafts is signaled to a transmission control unit. For this purpose, a rotational speed at which the synchronizer clutch rotates on one of the transmission shafts in an idling position or in an engagement position with one of the gears of a gear pair of a gear is first measured as the actual rotational speed. A desired speed to which the transmission shaft is to be accelerated or decelerated for a preselected gear is given by the transmission control unit. Synchronization parameters are controlled so that a rapid axial displacement of the synchronizer clutch on the transmission shaft from an idle position to an engaged position of the synchronous clutch of the preselected gear can take place. In this case, a required axial thrust force or an axial thrust speed of a shift claw of the synchronizer clutch is regulated depending on the speed.

With the help of the speed-dependent control of the thrust or an axial thrust speed of a shift claw can be taken to ensure that it comes to a speedy switching without it comes to the overshooting to a temporary notching of intermeshing sprockets. If such unlatching is detected by, for example, measuring a break in a speed curve or a torque transmission cutoff of the transmission shafts, synchronous parameters such as the axial thrust or axial shift speed with which a shift dog is displaced can be reduced, thereby slowing down or speeding up the speed a coupled transmission shaft can be reduced accordingly. The occurrence of load change noises can also be measured with acoustic sensors and fed back to an electronic control unit, which then correspondingly reduces the synchronization parameters until no load change noises are measurable.

With decreasing force on the synchronizer ring namely the frictional engagement between the synchronizer ring and the hub body of the corresponding gear and thus the deceleration or acceleration of the hub of the corresponding gear is reduced. At the same time, the decrease or increase in the rotational speed of one of the gear drive shafts, which is engaged with the gear to be synchronized via a non-rotatable drive gear, is correspondingly less slowed down or less accelerated. As a result of the reduction of the synchronization parameters overshoot can be reduced or an aperiodic limit between actual value and setpoint when switching from a gear to a higher or lower gear for the actual speed of the synchronization process with decelerated or accelerated transmission shaft can be achieved.

However, the so-called aperiodic limit case for the synchronization method according to the invention is not the optimum, although the transition from one gear to the next gear is relatively smooth, since it requires a much longer switching time.

In a preferred embodiment of the invention, it is therefore intended that a damped overshoot of the actual rotational speed of the transmission shafts at Upshifting or downshifting of the gears with respect to the target speed is limited to a speed difference between the actual value and target value that can not be exceeded by reducing the axial thrust force or the axial thrust speed of the shift claw of the synchronizer clutch. This speed difference for the overshoot is just such that the teeth of the output gear and the teeth of the drive gear remain engaged during shifting of the shift dog and overshoot of the actual speed.

Furthermore, it is provided that an oscillation frequency of a damped overshoot of the actual rotational speed of the transmission shafts when upshifting or downshifting the gears with respect to the target speed to a not to be exceeded oscillation frequency between the actual value and target value by reducing the axial thrust or the axial velocity of the shift claw Synchronous coupling is limited. If this oscillation frequency is exceeded, it may, as the following 1 shows, come to Lastwechselgeräuschen.

Another way to avoid such load change noise is a steepness of a damped overshoot of the actual speed of the transmission shafts when upshifting or downshifting the gears with respect to the target speed on a steepness not to be exceeded steepness of the speed change by reducing the axial thrust or Limit axial speed of the shift claw of the synchronizer clutch.

Is the steepness, as with 6 has been shown, too high, it comes to a notching between the teeth of the drive gear and the drive gear and to a periodic reconnection, which disadvantageously causes the load change noise of the transmission. In this respect, it is advantageous to correspondingly reduce the steepness of the rotational speed with which a damped overshoot of the actual rotational speed of the transmission shafts occurs during upshifting and downshifting of the gears, thereby providing reduced overshoot of the rotational speed during deceleration and acceleration during the gearshift.

In summary, it should be noted that a damped overshoot of the actual speed with respect to slope, oscillation frequency and speed difference to the target speed of the transmission shafts when upshifting or downshifting the gears by reducing the axial thrust force and / or the axial speed of the shift claw of the synchronizer clutch so limited is that the meshing teeth of the sprockets of the gear pair of a preselected gear remain engaged after engaging a synchronous clutch constantly.

Use of such a synchronization method is advantageous for operating an automatic dual-clutch transmission with two transmission input shafts, especially as more than one single synchronizer clutch is to be actuated in a shift operation in a dual-clutch transmission. Nevertheless, the principles of this method of synchronization are also advantageously applicable to operating an automatic single-speed transmission single-clutch transmission.

The invention will now be explained in more detail with reference to the accompanying figures.

1 schematically shows a diagram of the acceleration of rotational speeds of a transmission shaft according to a synchronization method of the invention when downshifting a gear;

2 Fig. 12 schematically shows a diagram of accelerating rotational speeds of a transmission shaft according to a synchronization method of the invention in downshifting from a fourth speed to a second speed of a dual clutch transmission;

3 schematically shows a diagram of an aperiodic limiting case of accelerating rotational speeds of a transmission shaft according to a gentle synchronization in downshifting from a fourth gear to a second gear of a dual-clutch transmission;

4 shows a schematic diagram of a dual-clutch transmission according to the prior art;

5 shows a double-acting synchronizer clutch according to the prior art;

6 schematically shows a diagram of the acceleration of rotational speeds of a transmission shaft with the formation of load noise.

1 schematically shows a diagram of the acceleration of rotational speeds of a transmission shaft according to a synchronization method of the invention when downshifting a gear. For this purpose, the time t is provided on the abscissa and the speed is plotted on the ordinate in revolutions per minute. On downshifting, from a higher gear to a lower gear, the corresponding output gear on a transmission output shaft must be accelerated by a synchronous disk of a synchronizer clutch to the speed of the transmission output shaft. This can be done in a dual-clutch transmission of a driven gear of the next low gear of a free-running transmission input shaft of the two existing in a dual clutch transmission drive shafts, without the need to disengage the engaged synchronizer clutch of the higher gear.

So it is in a dual clutch transmission temporarily two synchronizer clutches with corresponding output gears engaged and only by switching the engagement states of the two engine clutches in the dual clutch power flow is redirected from the originally engaged synchronizer clutch of the higher gear to the additional engaged synchronizer clutch of the lower gear. However, since the gear change only from odd to even and from even to odd gears in the dual clutch transmission can be done, a single input or disengagement of multiple synchronous clutches or a repeated engagement and disengagement of multiple synchronizer clutches is required for a change from a fourth gear to a second gear.

This means that the shortest possible time periods for the engagement and disengagement of the synchronizer clutches are provided. However, it may come to Lastwechselgeräuschen, as shown by the dot-dash line of the speed n _LWG . In this case, after exceeding the target speed n _soll and exceeding a speed difference of .DELTA.n the meshing teeth of the output gear and drive gear are no longer engaged and only at the times t ₁ to t ₅ with release of load change noise comb the teeth back together.

These load change noises occur when a slope α is exceeded and / or the maximum speed difference Δn _{max is} exceeded in the overshoot and / or the oscillation frequency of 1 / .DELTA.t _P exceeded with t _P as the period of a period of overshoot or a permissible period of Period is undershot. Such an overshoot occurs, as already described above, when an excessive axial thrust force is exerted on the shift claw and thus on the synchromesh and / or if an excessive thrust speed with which the shift claw on the synchromesh to the dog gear of the hub of the Output gear is moved, is present.

According to the invention, these synchronization parameters are therefore reduced so far with the aid of the transmission control unit that the maximum speed difference between n _soll and n _is not exceeded and the slope is likewise reduced to the extent that overshooting is only possible to a limited extent. Finally, the oscillation frequency is limited so far that load change noises are reduced or completely suppressed.

In addition to the measurement and the comparison of the rotational speeds of the two gear drive shafts and the transmission output shaft and the motor shaft with the aid of a corresponding evaluation within the transmission control unit, the occurrence of load noise in the transmission can also be monitored by an acoustic sensor and accordingly the synchronization parameters can be reduced so long until no load change noises are detected by the acoustic sensor. By reducing the synchronization parameters is in 1 achieved that the maximum overshoot at 100 ' . 200 ' . 300 ' . 400 ' and 500 ' on overshoot maxima 100 . 200 . 300 . 400 remain reduced within the maximum speed difference Δn.

2 schematically shows a diagram of the acceleration of rotational speeds n _is a transmission shaft according to a synchronization method of the invention when downshifting from a fourth gear at speed n _V4 to a second gear at speed n _V2 via a third gear at speed n _V3 . In this implementation example of the synchronization method, a shortest switching period of .DELTA.t _{S is} achieved, since an overshoot by the maximum speed difference .DELTA.n for the target speed n _{soll of} the second gear with n _{V2 is} allowed. Since in a dual-clutch transmission downshift over two gears, z. B. from a fourth to a second gear, briefly, the third gear is involved, is also at the speed n _V3 , whose course with a double-dot line in 2 is marked, a slight overshoot recognizable when both clutches are opened.

3 schematically shows a diagram of an aperiodic limiting case of accelerating rotational speeds of a transmission shaft according to a smooth synchronization when downshifting from a fourth gear at the speed n _V4 to a second gear at the speed n _{V2 of} a dual-clutch transmission. Components having the same functions as in the previous figures are identified by the same reference numerals and will not be discussed separately.

It can be clearly seen that the slope is flatter in the aperiodic limit than the slope α in 2 or in 1 , Also, the time interval .DELTA.t _S for switching is significantly greater than in 2 in which an overshoot is allowed within limits. Such a smooth switching from a higher gear to a lower gear also allows only a correspondingly adapted slowed driving of the vehicle.

The 4 to 6 were already discussed at the beginning, so that a repetition at this point is unnecessary.

LIST OF REFERENCE NUMBERS

1

automatic transmission

3

motor shaft

4

Double coupling

5

shifting claw

6

first engine clutch

7

second engine clutch

8th

first transmission input shaft

9

second transmission input shaft

10

Gearbox output shaft

11

synchronous clutch

12

synchronous clutch

13

synchronous clutch

14

synchronous clutch

15

Transmission control unit

22

Tachometer (first transmission input shaft)

23

Tachometer (second transmission input shaft)

24

Tachometer (transmission output shaft)

25

Tachometer (engine output shaft)

26

shift fork

29

Claw ring gear

30

Drive gear (reverse gear)

31

Drive gear (first forward gear)

32

Drive gear (third forward gear)

33

Drive gear (fifth forward gear)

34

Drive gear (second forward gear)

35

Drive gear (fourth forward gear)

36

Drive gear (sixth forward gear)

37

middle synchronizer ring

38

inner synchronizer ring

39

outer synchronizer ring

40

Output gear (reverse gear)

41

Output gear (first forward gear)

42

Output gear (third forward gear)

43

Output gear (fifth forward gear)

44

Output gear (second forward gear)

45

Output gear (fourth forward gear)

46

Output gear (sixth forward gear)

47

needle roller bearings

48

gear hub

49

Synchronkupplungsnabe

50

Cone of the outer synchronizer ring

V1

1. forward gear

V2

2nd forward gear

V3

3. Forward gear

V4

4. Forward gear

V5

5th forward gear

V6

6. Forward gear

R

reverse gear

n _is

Actual speed

n _should

Target speed

.DELTA.n

Speed difference

f _Osz

oscillation

α

steepness

α _max

not to be exceeded steepness

Claims (7)

Synchronization method for an automatic transmission ( 1 ) for vehicles, wherein - when upshifting or downshifting gears (V1 to V6 or R) the actual speed (n _is ) of transmission shafts ( 8th . 9 . 10 ) to a transmission control unit ( 15 ) is first signaled as actual speed (n _is ) a speed at which a synchronizer clutch ( 11 . 12 . 13 or 14 ) on one of the transmission shafts ( 10 ) in an idle position or in an engaged position with one of the gears ( 41 to 46 or 40 ) of a gear pair ( 31 / 41 . 32 / 42 . 33 / 43 . 34 / 44 . 35 / 45 . 36 / 46 or 30 / 40 ) of a gear (V1 to V6 or R) is rotated, measured and - a target speed (n _soll ), to which a transmission shaft ( 10 ) for a preselected gear (V1 to V6 or R) is to be accelerated by the transmission control unit ( 15 ), and - synchronization parameters are controlled in such a way that a rapid axial displacement of the synchronizer clutch ( 11 . 12 . 13 or 14 ) on the transmission shaft ( 10 ) from an idle position to an engaged position of the synchronizer clutch ( 11 . 12 . 13 or 14 ) of the preselected gear (V1 to V6 or R), wherein a required axial thrust force or an axial thrust speed of a shift claw ( 5 ) of the synchronizer clutch is controlled speed-dependent. Synchronization method according to claim 1, characterized in that a damped overshoot ( 3 ) the actual speed (n _is + Δn) of the transmission shafts ( 8th . 9 . 10 ) When upshifting or downshifting of the gears (V1 to V6 or R) with respect to the target speed (n _soll ) to a not to be exceeded speed difference (Δn) between the actual value (n _is ) and setpoint (n _soll ) by reducing the axial thrust or the axial pushing speed of the shift claw ( 5 ) of the synchronous coupling ( 11 . 12 . 13 or 14 ) is limited. Synchronization _method according to Claim 1 or Claim 2, characterized in that an oscillation frequency (f _Osz ) of a damped overshoot of the actual rotational speed (n _is + Δn) of the transmission shafts ( 8th . 9 . 10 ) When upshifting or downshifting the gears (V1 to V6 or R) with respect to the target speed (n _soll ) to a not to be exceeded oscillation frequency (f _Osz ) between the actual value (n _is ) and target value (n _soll ) by reducing the axial thrust or the axial speed of the shift claw ( 5 ) of the synchronous coupling ( 11 . 12 . 13 or 14 ) is limited. Synchronization method according to one of the preceding claims, characterized in that a steepness (α) of a damped overshoot of the actual rotational speed (n _ist ) of the transmission shafts ( 8th . 9 . 10 ) when shifting up or downshifting the gears (V1 to V6 or R) with respect to the target speed (n _soll ) to a steepness (α _max ) not to be exceeded by reducing the axial thrust force or the axial speed of the shift claw ( 5 ) of the synchronous coupling ( 11 . 12 . 13 or 14 ) is limited. Synchronization method for a dual-clutch transmission of a vehicle, wherein a damped overshoot of the actual speed (n _is ) with respect to slope (α), oscillation frequency (f _osc ) and Speed difference (Δn) to the desired speed (n _soll ) of the transmission shafts ( 8th . 9 . 10 ) when upshifting or downshifting the gears (V1 to V6 or R) by reducing the axial thrust force and / or the axial speed of the shift claw (FIG. 5 ) of the synchronizer clutch is limited such that the meshing teeth of the sprockets ( 27 ) of the gear pair ( 31 / 41 . 32 / 42 . 33 / 43 . 34 / 44 . 35 / 45 . 36 / 46 ) of a preselected gear (V1 to V6 or R) after engagement of a synchronous clutch ( 11 . 12 . 13 or 14 ) stay engaged. Use of the synchronization method according to one of the preceding claims for operating an automatic dual-clutch transmission ( 1 ) with two gear drive shafts ( 8th . 9 ). Use of the synchronization method according to any one of claims 1 to 5 for operating an automatic single-clutch transmission with a single transmission input shaft.

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